In the field of circuit design, it is common to write program in an integrated circuit (IC) chip to provide circuit functions in firmware form. The program that is written in the IC chip is generally not intended to be disclosed. However, a conventional IC package cannot protect the program codes written therein from unauthorized duplication. For example, program codes of a circuit may be accessed by detecting radio frequency emission from pins of the IC chip during the operation thereof or the codes may be directly accessed by electrically contacting the pins of the IC chip.
Thus, it is desired to have a security box for an IC chip which prevents program codes written therein from unauthorized copy.